Modern gasoline engines and diesel engines require increasingly efficient solenoid injectors in order to meet the demands for reducing fuel consumption and pollutants, for example. Rapidly switching solenoid injectors are manufactured using magnetically soft materials, such as FeCr alloys or FeCo alloys, or powder composite materials having an intrinsic electrical resistance as high as possible. However, due to alloy-associated measures, only an intrinsic electrical resistance of 1 μΩm maximum is achievable in metallic materials.
Furthermore, a magnetic material composed of iron powder and an organic bonding agent may be used in valves for diesel injection (common rail system). Although these materials have higher intrinsic electrical resistances than the aforementioned magnetically soft alloy materials, they are limited in many cases with respect to their fuel stability and thermal stability and are also poorly processable.
German Published Patent Application No. 199 60 095 describes a sintered magnetically soft composite material and a method for its manufacture in which a ferromagnetic starting component as the main component and a ferritic starting component as a minor component are used in a starting mixture from which, after a heat treatment, a magnetically soft composite material is formed. After the heat treatment of the starting mixture forming the composite material, the second starting component represents a grain boundary phase. The first starting component is a pure iron powder or a phosphatized iron powder, for example; the second starting component is a ferrite powder, e.g., a soft ferrite powder, such as MnZn ferrite or NiZn ferrite. The proportion of the iron powder in the starting mixture equals 95 percent to 99 percent by weight, and the proportion of the ferrite powder equals 1 percent to 25 percent by weight.